Oxygen and carbon isotope composition of parasitic plants and their hosts in southwestern Australia

被引:55
作者
Cernusak, LA
Pate, JS
Farquhar, GD
机构
[1] Australian Natl Univ, Res Sch Biol Sci, Environm Biol Grp, Canberra, ACT 2601, Australia
[2] Australian Natl Univ, Res Sch Biol Sci, Cooperat Res Ctr Greenhouse Accounting, Canberra, ACT 2601, Australia
[3] Univ Western Australia, Fac Nat & Agr Sci, Sch Plant Biol, Nedlands, WA 6907, Australia
关键词
holoparasite; mistletoe; resource acquisition; root hemiparasite;
D O I
10.1007/s00442-004-1506-6
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
We measured leaf dry matter delta(18)O and delta(13)C in parasitic plants and their hosts growing in southwestern Australia. Parasite/host pairs included two mistletoe species, three species of holoparasites, and five species of root hemiparasites. Among these parasite functional types, significant variation was observed in parasite/host isotopic differences for both delta(18)O (P<0.0001, n=65) and delta(13)C (P<0.0001, n=64). Mistletoes were depleted in both O-18 and C-13 compared to their hosts; parasite/host differences were -4.0parts per thousand for delta(18)O (P<0.0001) and -1.9parts per thousand for delta(13)C (P<0.0001). The lower delta(18)O in mistletoe leaf dry matter compared to their hosts is consistent with the frequently observed high transpiration rates of these parasites. Root hemiparasites were also depleted in O-18 and C-13 compared to their hosts, but not to the same extent as mistletoes; parasite/host differences were -1.0parts per thousand for delta(18)O (P=0.04) and -1.2parts per thousand for delta(13)C (P=0.0006). In contrast to mistletoes and root hemiparasites, holoparasites were enriched in both O-18 and C-13 compared to their hosts; parasite/host differences were +3.0parts per thousand for delta(18)O (P<0.0001) and +1.5parts per thousand for delta(13)C (P=0.02). The enrichment in O-18 for holoparasite dry matter did not result from more enriched tissue water; holoparasite tissue water delta(18)O was less than host leaf water delta(18)O by a difference of -3.8parts per thousand when sampled at midday (P=0.0003). Enrichment of holoparasites in C-13 compared to their hosts is consistent with a generally observed pattern of enrichment in heterotrophic plant tissues. Results provide insights into the ecology of parasitic plants in southwestern Australia; additionally, they provide a context for the formulation of specific hypotheses aimed at elucidating mechanisms underlying isotopic variations among plants.
引用
收藏
页码:199 / 213
页数:15
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